.taiji{
    margin: 200px auto;
    width: 392px;
    height: 196px;
    background: white;
    border-color: black;
    border-radius: 100%;  
    border-style: solid;
    border-width: 4px 4px 200px 4px;
    position: relative;
}
.taiji:before{
    content: "";
    width: 78px;
    height: 78px;
    background: black;
    border-color: black;
    border-radius: 100%;
    border: 59px solid white;
    top: 50%;
    left: 0;
    position: absolute;
}
.taiji:after{
    content: "";
    width: 78px;
    height: 78px;
    background: white;
    border-color: white;
    border-radius: 100%;
    border: 59px solid black;
    top: 50%;
    left: 50%;
    position: absolute;
}